Recycling non-ferrous metals is a way to preserve the resources of our planet and earn money for those who sell scrap to recycling centers. In the latter case, a person faces the task of distinguishing copper from other non-ferrous metals without laboratory tests, at home.
Copper, which is fou
nd in nature in the form of nuggets or ores, is indispensable in electrical engineering and the demand for this metal is constantly growing. In everyday life, there are often alloys of this metal, which can be distinguished from pure copper by using different techniques. Therefore, the question of what to do with a scrap car is not.
How to distinguish copper from other metals
In addition to determining the degree of purity of waste and scrap non-ferrous metals is required to determine their belonging and find out – is it a copper part, bronze, brass or made of another alloy.
Among all representatives of the group of non-ferrous metals, only copper, gold, cesium and osmium are characterized by the same coloring. A visually detectable red-brown with pink shades (in daylight) on a fresh cut or oxidized surface confirms the authenticity of the material. Copper conductors of electrical wires can be used as a specimen – they are made of a metal that does not contain any foreign impurities.
If a magnet interacts with a metal that visually resembles copper, it is its alloy. In some products, copper plating is applied to the aluminum base, which also does not have magnetic properties, so it will help to clarify the result of the test by examining the cut.
When a fragment of the metal under analysis is heated over an open flame, the copper surface will first lose its luster and become dull, and then it will acquire a blackish-brown hue. There is no smoke or pungent odors while heating pure copper, otherwise you are holding an alloy in your hands.
How to distinguish copper from brass and bronze
Both brass and bronze are derivatives of copper. In the first case it is an alloy with zinc, in the second – with tin, and with a small content of these components it is very difficult to identify the metal by color.
It is possible to distinguish copper from another metal by chemical means:
in the area of exposure to nitric acid (one drop is enough), the copper surface will acquire a characteristic blue-green hue;
Copper elements do not change color upon contact with hydrochloric acid (the reagent can only cleanse them of their patina), and on the surface of the brass, such exposure produces a white scum (zinc chloride);
In a solution of salt heated to 50 ° C (200 g of salt per 1 liter of water), copper, after 15-20 minutes, changes color, and the bronze is not susceptible to similar effects.
Copper is softer than brass and bronze, but a comparison on the bend may not be quite accurate due to differences in the parameters of products. A reliable way to check is to remove chips. Pure copper – soft, pliable and pliable – curls into a curl, while brass shavings remain in the form of a straight needle-shaped strip.
Manual pressure on the copper surface with a metal object leaves an indentation, while bronze withstands such stresses without visible consequences.